Bending machine for steel bars



Oct. 6, '1964 Filed March 21, 1961- C. BREDE BENDING MACHINE FOR STEEL BARS 2 Sheets-Sheet l INVENTOR Ch gzg stian Brede 2 Sheets-Sheet 2 Filed March 21, 1961 fi 2 I a 25 INVENTOR lzrzstzan Brede United States Patent Office 3,ll,656 Patented Oct. 6, T964 3,151,656 BENDhi-G MACHINE FQR STEEL BARS Christian Br de, Cologne, Germany, assignor, by mesne assigments, to Tor-lsteg Steel Corporation SAE Luxembourg, Luxembourg Filed 21, 1961, Ser. No. 97,258 Claims priority, application Germany Mar. 25, 196i; 7 Claims. (Cl. 153-49) This invention relates to a bending machine for forming bends, hooks and the like on reinforcements to be used in concrete.

It is known that a plurality of diiferent sizes of bending dies, for example, bending rollers, bending segments and the like, are required for bending bar-shaped steel reinforcements on bending machines. The number of such dies depends on the thickness and on the quality of the steel of the bars which are to be bent, the kind of bend required, and the position of the bent steel reinforcements in the ferroconcrete building part. interchanging the various dies in conventional bending machines often presents great difficulties, above all, in the case of relatively large bending rollers, which are of considerable weight and therefore cumbersome. In many cases, therefore, the larger rollers which should be used according to the requirements stipulated for ferroconcrete, are not used. The result is that the bends in most cases do not correspond to the prescribed curvatures.

In order to avoid, at least partly, the continual interchanging of the various dies for the bending of steel reinforcements, among other things use has already been made of a bending tool comprising dies wherein the bearing surfaces are not curved in accordance with one bending radius but in accordance with two different bending radii. Reinforcement bending machines are also known which have a rotatable bending turntable, an eccentric gripper, a shiftable abutment element, and annular bending dies which are mounted one within the other and concentrically about the central axis of the bending turntable, the outer bending die being axially displaceable into the working position. Keeping a second die in readiness above the bending plane in an inoperative position does not offer any substantial improvement as regards the use of the machine as compared with the hitherto often-used method wherein only two dies can be used alternately and the interchanging of these twin dies is also very difficult. in addition, the relatively high structure required for maintaining the unneeded second die is a hindrance when working at the bending machine. Instead of a plurality of individual dies, a relatively large number of twin dies have to be continually interchanged, in order to permit adaptation to different bending requirements.

An object of the present invention is the further improvement and development of bending machines of the kind specified, in order to simplify manipulation so that the prescribed bending radius can easily be adhered to in each case.

According to the present invention there is provided a bending machine for bending reinforcements for use in concrete, said machine comprising a rotatable turntable, a plurality of annular bending dies mounted one within the other concentrically about a central pivot of the turntable, said bending dies, when in an inoperative position, being located below a working surface of the turntable, means for axially displacing the bending dies selectively into a raised working position in which the selected die can be engaged by a bar to be bent, said machine comprising also an abutment and a displaceable gripper adapted, during a bar bending operation, to guide and to engage the bar with the selected bending die.

A bending machine embodying the invention has the advantage that practically all the dies with the necessary bending radii are not only readily available in the bending machine but can also be rapidly brought into the Workin position. The arrangement of the dies below the working surface of the bending turntable leaves the area above the bending turntable free for carrying out the bending Work without hindrance. There is no difiiculty in changing the machine over to working with different dies, and this can .be carried out by hand or automatically. All that has to be done is to adjust the desired setting just as on other machine tools, whereupon the desired die with the appropriate bending radius or some other curvature is moved outwards by hand operation or by means of motor force.

For a better understanding of the invention and to show how the same may be carried into efiect, reference will now be made by way of example, to the accompanying drawings, in which:

FIG. 1 is a diagrammatic plan View of a bending machine,

PiG. 2 is a sectional view on the line 22 of FIG. 1, and

P16. 3 is a horizontal sectional view on the line 3--3 or" FIG. 2.

Referring to the drawings, the bending machine has a bending turntable 1 that is cup-shaped as illustrated in section in FIG. 1 and has rising from the bottom wall 1a a central spindle 2 and accommodated Within the cupshaped turntable 1 that is of annular formation are the individual dies which form the bending rollers and these dies are also of annular or ring shape, and while any number of such dies may be employed, there are shown five such dies respectively designated 3a, 3b, 3c, 3d, and 3e, with the center ring die 30. contacting the spindle 2 and with the other dies all being substantially contiguous with each other and confined in the cup-shaped turntable 1. These dies when in the inoperative position have their upper surfaces in the plane of the upper surface of the turntable 1. All the dies 35: to Be, therefore, form together with the bending turntable 1 a single Working surface which is situated at the level of a table 5 surrounding the bending turntable 1. The central spindle 2 projects upwardly above the working plane 4 and at the same time constitutes an additional bending die, i.e. a bending roller with the smallest bending radius. The drive of the hen ing turntable 1 may be accomplished in various ways and one sample is illustrated in PEG. 2 wherein the cupshaped turntable 1 carries a depending shaft 2a aligned with the spindle 2 with the bevel gear 6 at the lower end thereof that meshes with the bevel gear 7 driven by the motor 8. Alternatively, the bending turntable 1 may be provided with a peripheral toothed rim which engages with suitable means on the driving device.

The dies 3a and 3e are adapted to be lifted into the worldng position from the lowered position, and in order to prevent the individual dies from being deformed, particularly when bending relatively large bar diameters, when the selected die is lifted all the next smaller dies are simultaneously lifted into the working position. This is achieved by arranging the vertically adjustable dies to engage below one another. All of the dies except the die So have at their inner side a projection or preferably an annular collar 9 which engages in a correspondingly shaped groove 1-? in the adjoining inner die. In this way, the bending roller formed by the group of dies in each particular case is supported by its components bearing against one another in the radial direction as far as the central spindle 2.

To effect the die lifting operation each die 3a to 3e is provided with two racks i1, 12, 13, 1- or 15, respective 13*, disposed at diametrically opposite sides of the die and '1 n r extending in a direction axially of the die. The racks extend through corresponding guides 18 in the bottom 1a of the bending turntable 1 and are adapted to mesh with pinions 16 and 17 which are mounted on a shaft 19 so as to be'secured against rotation thereon but longitudinally displaceable on the said shaft. The sliding of the two pinions from one pair of racks to the next is effected by means of a spindle 20 the center of which is mounted on a bridge 21 which at the same time also comprises the central bearing of the shaft 19. The spindle 20 is provided at one'end with an external right-hand screwthread and at the other end with an external left-hand screwthread. The ends of the spindle 20 and of the shaft 19 are mounted in lugs 22 and 23 which are fast with the turntable 1 as shown in FIG. 1. Nuts 24 and 25 are respectively threaded on the spindle 29 at opposite sides of the bridge '21 and are suitably held against rotation. Each nut 24 and 25 is provided with arms 26 and 27 which are fixedly secured to the nut and form a fork whose arms receive the pinions 17 and 16 respectively between them. Both the shaft 19 and the spindle 20 we provided at one end with square portions 28 and 29 in order that cranks may be fitted to said ends for manual rotation of the respective shaft. Vfhen the spindle 29 is rotated, the gearwheels 16 and 17 are displaced in the axial direction by the traveling nuts 24 and 25. In the illustrated form of embodiment, the gearwheels 16 and 17 are in engagement with the racks 12 of the die 3b. After the gearwheels 16 and 17 have been brought into engagement with the desired pair of racks by rotation of the spindle 29, the shaft 19 is then rotated by means of the square end 28, to bring the die 3b into the working position as shown in FIG. 2. Owing to the fact that the die 3b engages below the die 3a, the die 3a also moves simultaneously into the working position, thus providing a bending roller having the radius of the die 3b and reinforced by the radially inner dies. In the same way, any other die can be lifted to the working position.

Depending on the size of the bending turntable and the number of the dies put into use, a transmission gear may also be provided if necessary. In the case of bending ma chines for iron reinforcements for use in concrete structures, on which larger bends are executed, the lifting and lowering of the dies is conveniently carried out by motor power. In order to secure the dies in the working position, theshaft 19 on which the gearwheels 16 and 17 are mounted, can be locked in the particular position of rest. The actual position of the two gearwheels 16 and 17 at any moment can be registered on a visual indicating device arranged on the control station (not shown).

The bending turntable 1 is provided with a number of holes 31? which are adapted to receive a gripper 31 which can be mounted by mems of a pin or the like in one of the holes 31] in accordance with the bend which has to be executed. In order to permit the free spacing between the gripper, and the die to be varied, the gripper roller is eccentrically mounted. A further variation of the free spacing between the actual die and the gripper wall can be effected, for example, by using an elliptical gripper roller which is mounted on a shaft of polygonal cross-section which is mounted in an appropriate hole in the cup wall of the bending turntable 1. If necessary, the elliptical gripper roller may be formed with additional holes to provide more possibilities of variation. The table 5 is formed at the sides with a series of holes 32 adapted to receive a fixed abutment element 33.

Referring to FIG. 1, a steel reinforcement bar 34 is to be formed with a hook, and bears against the lifted die 3b. The gripper 31 keeps the end of the steel reinforcement 34 pressing against the die 3b. The abutment element 33 mounted in the appropriate hole 32, provided in the table 5, prevents the steel bar from swinging outwards as the bar is drawn into the machine during the bending operation. When the bending turntable 1 rooneness In order to avoid the rolling skin or scale which falls oif the steel reinforement bars, when the latter is being bent, from resulting in jamming of the individual dies, the play between the individual dies can be so considerable as to allow the dies to be deformed elastically but not plastically. In this way, the scale produced during bending can fall downwards through these clearances. This can be further promoted by arranging additional grooves or channels on the inner side i.e. the hollow side, of the bending dim. Furthermore, the individual dies do not lie fiush on the bottom of the cup but a small clearance is left between the lower edge of the die and the bottom of the cup, from which the accumulating scale can .be removed from time to time.

The machine for bending steel reinforcements for concrete according to the invention may alternatively be constructed as a hand-operated bending device.

The adjustment of the gripper roller can be efiected either by rotational movement about its eccentrically mounted shaft, by further vertical holes arranged in the Wall of the dies, or for example by a roller which is adjustable with the help of a guide spindle from the outside towards the inside, i.e., towards the center point of the turntable.

In addition, the dies may be locked e.g. by pins or the like, in the raised position, and it is also convenient to provide a blocking device to ensure that the change-over of the actuating device to the next die can only take place when all the dies are in the lowered position.

What is claimed is:

1. A bending machine for bending reinforcements for use in concrete, said bending machine comprising a stationary horizontally disposed table, a ring-shaped rotatable turntable disposed within said stationary table for rotation relative thereto about a vertical axis, a plurality of full circle annular bending dies mounted one within,

the other and disposed within the rotatable turntable for rotation therewith, means carried by said stationary table for selectively engaging each of said bending dies for raising the same above the plane of said tables, a displaceable gripper, means selectively mounting said gripper on said turntable to engage a bar to be bent with a selected one of said bending dies during a bar bending operation, an abutment element, and means selectively mounting said abutment element on said stationary table for guiding a bar during a bar bending operation.

2. A bending machine according to claim 1, wherein the bending dies are provided at the lower ends thereof with interengaging means comprising an annular collar at the radially inner side of each die except the central die and a corresponding groove at the radially outer side of all dies whereby when lifting a die into working position, all of the smaller enclosed dies are lifted therewith except the outermost die.

3. A bending machine as in claim 2, wherein two racks i depend from each die, and the means for raising said bending dies includes a shaft mounted below the turntable with a pair of gears slidable thereon and rotatable therewith and means for moving the gears into selective engagement with said pairs of racks.

4. A bending machine as in claim 2, wherein two racks depend from each die, and the means for raising said bending dies includes a shaft mounted below the turntable with a pair of gears slidable thereon and rotatable therewith and means for moving the gears into selective engagement with said pairs of racks comprising a threaded shaft paraxial with the aforesaid shaft and nuts on said 5 threaded shaft having means engaging the gears to move them into selective engagement with said racks.

5. A bending machine as in claim 1, wherein two racks depend from each die, and the means for raising said bending dies includes a shaft mounted below the turntable with a pair of gears slidable thereon and rotatable therewith, and means for moving the gears into selective engagement with said pans of racks.

6. A bending macmne as in claim 1, wherein two racks depend from each die, and the means for raising said bending dies includes a shaft mounted below the turntable with a pair of gears slidable thereon and rotatable therewith, and means for moving the gears into selective engagement with said pairs of racks comprising a threaded shaft paragn'al with the aforesaid shait and nuts on said threaded shaft having means engaging the gear to move them into selective engagement vith said racks.

7. A bending machine for bending reinforcements for use in concrete, said machine comprising a stationary horizontally disposed table, a ring-shaped rotatable turntable disposed Within said stationary table for rotation about a vertical axis, a plurality of annular bending dies of ring-shape mounted one within the other and within the rotatable turntable for rotation there; means selectively engageable with one of the ring-shaped bending dies for raising it to an operative position above the top of the stationary table, and inter-fitting connections between all of the bend g dies whereby all bending dies located within the ring-shaped die being engaged to be elevated are elevated therewith so that the raising of the outermost ring-shaped bending die will cause all of the enclosed bending dies to be simnltaneously elevated, two racks depending from each die, means for raising said bending ies includes a shaft mounted below the turntable with a pair of gears slidable thereon and rotatable therewith, means for moving the gears into selective engagement with said pairs of racks comprising a threaded shaft paraxial with the aforesaid shaft, nuts on said threaded shaft having means engaging the gear to move them into selective engagement with said racks, a rod gripper carried by said turntable for holding the rod to be bent into engagement with the bending dies, and abutment means on the stationary table engaged by the outer end of the rod being bent.

References Qited in the file of this patent UNlTED STATES PATENTS 2,819,752 Hart Ian. 14, 1958 

1. A BENDING MACHINE FOR BENDING REINFORCEMENTS FOR USE IN CONCRETE, SAID BENDING MACHINE COMPRISING A STATIONARY HORIZONTALLY DISPOSED TABLE, A RING-SHAPED ROTATABLE TURNTABLE DISPOSED WITHIN SAID STATIONARY TABLE FOR ROTATION RELATIVE THERETO ABOUT A VERTICAL AXIS, A PLURALITY OF FULL CIRCLE ANNULAR BENDING DIES MOUNTED ON WITHIN THE OTHER AND DISPOSED WITHIN THE ROTATABLE TURNTABLE FOR ROTATION THEREWITH, MEANS CARRIED BY SAID STATIONARY TABLE FOR SELECTIVELY ENGAGING EACH OF SAID BENDING DIES FOR RAISING THE SAME ABOVE THE PLANE OF SAID TABLES, A DISPLACEABLE GRIPPER, MEANS SELECTIVELY MOUNTING SAID GRIPPER ON SAID TURNTABLE TO ENGAGE A BAR TO BE BENT WITH A SELECTED ONE OF SAID BENDING DIES DURING A BAR BENDING OPERATION, AN ABUTMENT ELEMENT, AND MEANS SELECTIVELY MOUNTING SAID ABUTMENT ELEMENT ON SAID STATIONARY TABLE FOR GUIDING A BAR DURING A BAR BENDING OPERATION. 